Pulmonary Hypertension

SEARCH Algorithm — Identifying Chronic Thromboembolism Phenotypes After Acute PE

• Authors: UCSD / Harbor-UCLA / Lundquist Institute group
• Journal / date: European Respiratory Journal, 2026
• DOI / URL: 10.1183/13993003.01562-2025 | PMID 41956701
• Source basis: Abstract only
• Study type: Prospective observational validation
• PH group: Group 4 (CTEPH + non-PH chronic thromboembolism phenotypes)
• Population: 150 consecutive patients ≥3 months after acute PE
• Tool (SEARCH):
• Symptom screen
• Cardiopulmonary exercise testing
• Pulmonary arterial perfusion scans
• Resting echocardiography
• Confirmatory imaging
• Hemodynamic measurements (rest + exercise RHC)
• Key findings:
• 66.2% had symptomatic recovery
• 19.7% had dyspnea from alternative diagnoses
• 12.0% had a chronic thromboembolism phenotype
• 6.3% chronic thromboembolism with ventilatory inefficiency / small stroke-volume augmentation on exercise
• 2.1% CTEPH
• 3.5% chronic thromboembolism with exercise-induced PH
• Inter-rater reliability among 6 readers: Krippendorff's α = 0.984 (very high)
• Why it matters (clinical takeaway):
• Practical diagnostic algorithm for the persistently dyspneic post-PE patient — most have alternative explanations, but ~12% have a chronic thromboembolic phenotype.
• Most chronic thromboembolism after PE is NOT classic CTEPH — the SEARCH framework recognizes exercise-induced PH and ventilatory-inefficiency phenotypes that would otherwise be missed.
• High reader agreement supports adoption across centers without requiring deep CTEPH expertise to apply.
• Caveats / limitations: Single-system cohort; algorithm requires CPET and rest+exercise RHC capability.
• Referenced trials pulled forward: None.